機電-體化專業(yè)英語Unit 7

1、Electronic Components and CircuitPart I Technical and Practical Reading Passage A Electronic Components and Symbols An electronic component is a basic electronic element and is usually packaged in a discrete form with two or more connecting leads or metallic pads. Components are intended to be conne

2、cted together, usually by soldering to a printed circuit board, to create an electronic circuit with a particular function (for example an amplifier, radio receiver, or oscillator). There are a large number of symbols which represent an equally large range of electronic components. It is important t

3、hat you can recognize the more common components and understand what they actually do. Diodes Diodes are basically a one-way valve for electrical current. They let it flow in one direction (from positive to negative) and not in the other direction. Most diodes are similar in appearance to a resistor

4、 and will have a painted line on one end showing the direction or flow (white side is negative). If the negative side is on the negative end of the circuit, current will flow. If the negative is on the positive side of the circuit, no current will flow. Transistors There are two types of standard tr

5、ansistors, NPN and PNP, with different circuit symbols. The transistor is possibly the most important invention of this decade. It performs two basic functions. 1) It acts as a switch turning current on and off. 2) It acts as an amplifier. This makes an output signal that is a magnified version of t

6、he input signal. Resistors Resistors, like diodes and relays, are another of the electronic parts that should have a section in the installers parts bin. They have become a necessity for the mobile electronics installer, whether it be fordoor locks, timing circuits, remote starts, LEDs, or just to d

7、ischarge a stiffening capacitor. Resistors resist the flow of electrical current. The higher the value of resistance (measured in ohms) the lower the current will be. Capacitors A device used to store charge in an electrical circuit. A capacitor functions much like a battery, but charges and dischar

8、ges much more efficiently (batteries, though, can store much more charge). A basic capacitor is made up of two conductors separated by an insulator, or dielectric.Thyristor The thyristor is a solid-state semiconductor device with four layers of alternating N and P-type material. They act as bistable

9、 switches, conducting when their gate receives a current pulse, and continue to conduct for as long as they are forward biased (that is, as long as the voltage across the device has not reversed). Some sources define silicon controlled rectifiers and thyristors as synonymous. Light-emitting Diode A

10、light-emitting diode (LED) is an electronic light source. LEDs are based on the semiconductor diode. When the diode is forward biased (switched on), electrons are able to recombine with holes and energy is released in the form of light. This effect is called electroluminescence and the color of the

11、light is determined by the energy gap of the semiconductor. LEDs present many advantages over traditional light sources including lower energy consumption, longer lifetime, improved robustness, smaller size and faster switching. Relay A relay is an electrically operated switch. Current flowing throu

12、gh the coil of the relay creates a magnetic field which attracts a lever and changes the switch contacts. The coil current can be on or off so relays have two switch positions and they are double throw (changeover) switches. Notes 1、It is important that you can recognize the more common components a

13、nd understand what they actually do. 本句為狀語從句。句中recognize和understand為并列結(jié)構(gòu)；而understand又引導(dǎo)出一個定語從句。全句可譯為：重要的是你能認(rèn)出常見的部件并了解它們到底是做什么用的。2、The coil current can be on or off so relays have two switch positions and they are double throw (changeover) switches. 本句為并列句，由并列連詞so引出；they指代relays。全句可譯為：線圈中可允許或阻止電流流過，所

14、以繼電器可處于開關(guān)兩個位置，可作為雙向開關(guān) (轉(zhuǎn)換開關(guān)) 。 1. An electronic component is a basic electronic element, which is often placed in a printed circuit board.2. Diodes are basically regarded as a two-way valve for electrical current.3. One of three basic functions for transistors is an amplifier.4. An insulator separat

15、es a basic capacitor into two conductors.5. Semiconductor diode is a kind of resistor. EXERCISE 1 Mark the following statements with T (True) or F (False) according to the passage. (T)(F)(F)(T)(F)1. electronic components _2. _ 金屬墊片3. one-way valve _4. _ 電流5. current pulse _6. _ 半導(dǎo)體裝置7. bistable swit

16、ches _ 8. _ 發(fā)光二極管 EXERCISE 2Translate the following phrases into Chinese or English. 電子元件 metallic pads單向閘electrical current電流脈沖semiconductor device雙穩(wěn)開關(guān)light-emitting diodePassage B Basic Circuit Concepts The figure shows the basic type of electrical circuit, in the form of a block diagram. It consi

17、sts of a source of electrical energy, some sort of load to make use of that energy, and electrical conductors connecting the source and the load. The electrical source has two terminals, designated positive (+) and negative (-). As long as there is an unbroken connection from source to load and back

18、 again as shown here, electrons will be pushed from the negative terminal of the source, through the load, and then back to the positive terminal of the source. The arrows show the direction of electron current flow through this circuit. Because the electrons are always moving in the same direction

19、through the circuit, their motion is known as a direct current (DC). The source can be any source of electrical energy. In practice, there are three general possibilities: it can be a battery, an electrical generator, or some sort of electronic power supply. The load is any device or circuit powered

20、 by electricity. It can be as simple as a light bulb or as complex as a modern high-speed computer. The electricity provided by the source has two basic characteristics, called voltage and current. These are defined as follows:Voltage The electrical pressure causes free electrons to travel through a

21、n electrical circuit, also known as electromotive force (EMF). There are two principal types of source, namely voltage source and current source.Sources can be either independent or dependent upon some other quantities. An independent voltage sourcemaintains a voltage which is not affected by any ot

22、her quantity. Similarly an independent current sourcemaintains a current which is unaffected by any other quantity Some voltage (current) sources have their voltage (current) values varying with some other variables. They are called dependent voltage (current) sources or controlled voltage (current)

23、 sources.Current A collection of devices such as resistors and sources in which terminals are connected together by connecting wires is called an electric circuit. These wires converge in nodes, and the devices are called branches of the circuit. The general circuit problem is to find all currents a

24、nd voltages in the branches of the circuit when the intensities of the sources are known. Such a problem is usually referred to as circuit analysis. Resistance When voltage is applied to a piece of metal wire (Figure 7-12), the current I flowing through the wire is proportional to the voltage V acro

25、ss two points in the wire. This property is known as Ohms law, which reads: V=IR or I+CV. where R is called resistance, G is called conductance. The resistance R and the conductance G of the same piece of wire is related by R = 1/G. Resistance is measured in ohms () and conductance in Siemens (S or

26、). The relationship between voltage, current, and resistance in an electrical circuit is fundamental to the operation of any circuit or device. Verbally, the amount of current flowing through a circuit is directly proportional to the applied voltage and inversely proportional to the circuit resistan

27、ce. By explicit definition, one volt of electrical pressure can push one ampere of current through one ohm of resistance. EXERCISE 3 Choose the best operation orders according to the information given. DFAHBJCIEG1. PCM Pulse Code Moduatio _2. P ds Potential Differences _3. PE Pressure Element _.4. P

28、DR Power Direction Relay _ 5. PF Power Factor _ 6. PL Pipe Line _ 7. PO Power Output _8. PT Potential Transformer _ EXERCISE 4Abbreviations are very useful in practical work. Read them and then translate them into corresponding Chinese terms. 脈碼編制位差壓力元件功率方向繼電器功率系統(tǒng)管路功率輸出變壓器Part II Glance at Conventio

29、nal Machine Tool Structures The following is the Vice Jaw Structures。 Explanations of the Transistor Terms No.NameExplanation1Collector集電極2Base基極3Emitter射極4Base-Collector junction基極集電極結(jié)5Base-Emitter junction基極射極結(jié)6NPNNPN型晶體管7PNPPNP型晶體管EXERCISE 5The following is the Vice Jaw. After reading them, you a

30、re required to choose the suitable words or phrases given below. Circuit 1 Circuit 2 Iron Rocker Arm PivotSwitch Contacts Motor Spring Part III Simulated WritingSection A Match Your SkillThe following is the Lathe Accessories, and you can understand the name of Inner Dial Caliper Gauge. Explanations

31、 of the Toll BitsNo.NameExplanation1Epoxy Dome Lens環(huán)氧樹脂封裝的透光帽2Bonding Wire焊線3Lead Frame引線框4Cathode ()陰極5Anode ()陽極6Phosphor熒光物質(zhì)7Light Waves光波8Light Emitting Diode發(fā)光二極管9Reflector Cup反光杯座EXERCISE 6Complete the information by translating the part given in Chinese. Product Specification (Light Emitting

32、Diode) Absolute Maximum Ratings (Ta = 25) ItemsSymbolAbsolute maximum RatingUnitPower DissipationPD100mWForward Current(DC)IF30mAPeak Forward Current*IFP100mAReverse VoltageVR5VOperation TemperatureToprStorage TemperatureTstgLead Soldering TemperatureTsolMax.260C for 5 sec Max. (3mm from the base of

33、 the epoxy bulb)Typical Electrical & Optical Characteristics ( Ta = 25)ItemsSymbolConditionMin.Typ.Max.UnitForward VoltageVFIF=20mA3.00/3.60VReverse CurrentIRVR=5V10uADominant WavelengthDIF=20mA465/475Luminous IntensityIVIF=20mA1800/2700mcd50% Power AngleIF=20mA15degTolerance of measurement of lumin

34、ous intensity: 15Tolerance of measurement of dominant wavelength: 1.0nmTolerance of measurement of forward voltage: 0.05VSection B Have a TryThis section will help you to understand several forms of machining, and you can see the simple way a small part is produced. Internal Operations Boring - An o

35、peration in which a boring tool enters the workpiece axially and cuts along an internal surface to form different features. The boring tool is a single-point cutting tool, which can be set to cut the desired diameter by using anadjustable boring head. Boring is commonly performed after drilling a ho

36、le in order to enlarge the diameter or obtain more precise dimensions. On a turning machine, a variety of features can be formed, including steps, tapers, chamfers, and contours. These features are typically machined at a small radial depth of cut and multiple passes are made until the end diameter

37、is reached. For a finish turning operation, the cutting feed is calculated based on the desired surface roughness and the tool nose radius.EXERCISE 7This section is to test your ability to Identifying following features of different operations. Bored hole Bored step Boring (Milling machine) Boring (

38、Milling machine)Bored holeBored stepPart IV Broaden Your Horizon - Practical Activity How to Repair NEC P8000 Printer Main Board Problem If the complaint for NEC P8000 printer was a missing line across the printout, immediately we will suspect the printer head or the ribbon or even sometime the ribb

39、on mask. Among so many brand of dot matrix printer, only this model have one common fault which is the printer head and the printer driver ics spoilt. If you just replace the printer head without changing the main board or checking the printer driver ic for any short circuit, then chances are high that once you switch on the printer, the printer head would immediately breakdown again. Thus it is wise for you, if you ever comes across this type of printer, besides replacing the printer head, you must check the six printer driver ic on the main board. As for the printer head, you can buy a